Escapement mechanism



July 12, 1955 R. G. scHAAF, JR 2,712,758

ESCAPEMENT MECHANISM Filed Nov. 2, 1948 ZNVENTOR.

HTTOFZNEY naiss mouth ileach, N. I., assigner n, N. Y., a

Application 2, 1943, No. 57,930

This invention relates to timing mechanisms or the like and moreparticularly to escapemcnt mechanisms and motion transmitting meansassociated therewith, including means for supporting rotatable parts orsuch and other mechanisms.

One of the objects of the present invention is to provide novelstructural features in a clock or other timing mechanism wherebyoperational noises are appreciably reduced.

Another object or" the invention is to improve .known types of timingmechanisms in such a manor as to insure more accurate and uniformoperation for longer periods of time.

A further object is to provide novel simplied mounting means for a rotat e shaft, such as the escapernent wheel device, whereby stabilizationot the axis ot rotation is assured and undesirable movement thereof iseliminated,

A still further object is to provide means for mounting a rotatableshalt in a novel manner to automatically obtain optimum braking ecctwhile at the same time providing improved lubrication facil es whichmaterially increase the dry-out time period.

Still another object is to provide an escapement mechanism wherein thenoise level is materially reduced by constructing parts, which aresubjected to impact, from materials not heretofore used in suchmechanisms.

Another object is to provide novel means for rotatably supporting ashaft whereby torsional resistance is reduced to desired minimum, andwhereby wear is reduced and automatically compensated.

The above and further obiects and novel features of the presentinvention will more fully appear `from the following detaileddescription when the same is read in conection with the accompanyingdrawings. lt is to be expressly understood, however, that the drawingsare for the purpose of illustration only, and are not intended as adefinition of the limits of the invention, reference for this latterpurpose bein had primarily to the appended claims.

ln the drawings, wherein like reference characters refer to like partsthroughout the several views,

Fig. l is a top plan view, partly in section with parts removed, of anelectrically actuated timing device embodying one form or the presentinvention, the sectio being taken substantially on line of 2, and theelectrical connections to a source of energy being showndiagrammatically;

Fig. 2 is a front elevation of the device shown in Fig. l;

Fig. 3 is an enlarged detail view of the balance wheel assembly embodiedin said device; and

Fig. is a still further enlarged detail view, partly in section andwitlI parts broken away, of one end of the escapement wheel shaft andthe mounting bracket there for.

Although the present invention may be incorporated in other types ofdevices and particularly in various other types of escapement mechanismsfor timing devices, the

single embodiment illustrated in the drawhgs, by way of example, isshown in the form or" an elec ic elo-cl; of the type employed inautomobiles and the like, the same being adapted for operation byelectrical e.. ergy from a storage battery. The noise created by theaverage timing devices, although not great when compared with othertypes of normal noises, is of sufficient magnitude and of such a natureas to be most annoying and nerve-racking. For example, the engines or"modern automobiles have been so perfected that the noise emanating froma clock mounted on the instrument panel can be heard by occupants of thecar even when the engine is ruiming. l have round that a substantialpart of this noise results from the operatic-n ot the cscapementmechanism, and it is accordingly a purpose of this invention to improvethat mechsin with a view to reducing the noise level thereof.

The clock in conjunction with which the invention is l"lustratedcomprises a balance wheel staff 5 journalled at its opposite ends injewelled bearings (not shown) suitably mounted in plates e and 7. Thelatter are secured together in superposed spaced relation by two pillars8, each having one end thereof secured to plate o and the opposite endextending through plate 7 and being externally threaded to receive a nut9.

Oscillatory motion of staff 5 is effected in part by a hair spring lllhaving one end secured to the stad and the other end anchored in stud ilwhich is fixed to and depends from plate 7. Motion is imparted tostai-t` 5 and energy is stored in hair spring l@ by electromagneticmeans which includes a balance wheel l2 of magnetic material, such asiron, mounted on the Staifor rotation therewith. As shown, the balancewheel comprises three circumferentially spaced pallets i3. A pair ofoppositely disposed pole pieces or shoes i4 and l5 are arranged adjacentthe path of movement of pallets i3, and the connected ends thereofconstitute a core on which a coil i6 is wound. Pole pieces 14 and i5 areprovided with openings through which pillars S extend and are rigidlyheld in proper position relative to armature .l2 through the medium ofSpacers l? which surround the pillars between the pole pieces and plate7. The connected pole pieces and l5, together with the armature l2,constitute a path for magnetic ilux created by variable current Flowthrough the winding of coil lo. Upon energization of the coil, balancewheel l2 will be urged in one direction of rotation or the other,depending upon the position at that time of pallets 13 with respect tothe pole shoes 14 Secured to the armature l2 and extending downwardlytherefrom, as viewed in Figs. 2 and 3 of the drawings, is a contact pinlo which is adapted to close an electrical circuit by making contactwith the free end portion of a resilient Contact linger constituted byflat spring 19, the other end of which is anchored to a post 2t) whichis in turn secured to and electrically connected with a conducting strip2l. latter is insulated from plate o and secured thereto by a screw 22that extends upwardly through said plate and strip 2l and has a nut 23threaded on the upper end thereof. interposed between strip 2li and nut23 is a tubular resistor 24 which, as will hereinafter appear, iselectively connected in shunt with the winding of coil 16. Means arealso provided for insulating the screw or bolt 22 from plate 6 andresistor 24. Strip 2i, and hence contact spring 19, is connecte to oneend of coil i6 by means of a con` ductor 25, the end portion of tweenstrip 2l and resistor 24. resistor is connected to the other end of thewinding of coil 16 by means of a conductor 26, the terminal of which isinterposed between the resistor and nut 23.

One terminal of a source of electrical energy, such as battery 253, maybe connected to terminal 22 by means of a conductor 27, and the otherterminal of the source which is interposed be- The other end of the maybe connected by a conductor 29 to a terminal post 30 secured to plate 6,which may be regarded as, and is in normal practice, a so-called groundconnection. The electrical circuit through the winding of coil 16 maythus be traced from battery 28, through ground or conductor 29, terminalpost 3G, plate 6, pillars 8, plate 7, stud 11, hair spring 1t), staff 5,armature 12, contact pin 1S, Contact spring 19, post 2i), strip 21,conductor 25, the winding of coil 16, conductor 26, terminal 22, andconductor 27 to the other terminal of battery 28. The resistor 24, beingconnected between the terminals of conductors 25 and 2n, is connected inshunt with the winding of coil 26 and is effective to prevent thecontacts 18, 19 against burning and corrosion during long use.

When the clock is stopped, the balance wheel or armature 12 is caused byhair spring 19 to assume the position shown in Fig. l. with contact pin15 in engagement with contact finger 19. `For the purpose of startingthe clock, a manually operated conductor (not shown) may be provided formomentarily connecting plate 7 directly to post 20 so that the coil 16may be momentarily subjected to the maximum energy of the battery.During energization of the coil in this manner, the magnetic flux acrosspole pieces 1e and 15 is effective to cause the armature 12 to move, letus say, in a clockwise direction as viewed in Pig. l. This initialmovement of the armature contracts hair spring 1u and causes contact pin1S to move out of engagement with contact spring 19, therebyinterrupting the circuit through coil 16. With the circuit deenergized,armature 12 is free to rotate in a counter-clockwise direction under theinuence of the energy stored in contracted hair spring 1t). Upon returnof wheel 34 to its initial position, the electrical circuit is againclosed through contacts 18, 19 and coil 16 is again energized, whereuponarmature 12, having been carried past its central position by momentum,is magnetically attracted in a counter-clockwise direction, therebyexpandmg hair spring 1lb beyond its neutral position and again movingcontact pin 18 out of contact spring 19. Coil 16 is thus againdeenergized and the armature is caused to rotate in a clockwisedirection by the energy of expanded hair spring 1d. This cycle ofoperation is periodically repeated as long as the battery is connectedacross the terminals 22 and 30, thereby sustaining the oscillatorymovement of the armature or balance wheel 12 and staff 5.

The oscillatory movement of shaft 5 may be transposed in a known mannerthrough an escapement mechanism into uni-directional motion of a geartrain which actuates the hands of a clock or other time-indicatingmeans. In the form shown, the escapement mechanism comprises a member 31(Fig. 3) secured to staff S for movement therewith, said member beingprovided with axially spaced, radially extending discs which form achannel and which are interrupted and bent to form two oppositelyinclined cams 32 and 33. The latter are effective in a known manner toalternately engage successive teeth on an escapement pinion or wheel 34during oscillation of staff 5 to impart intermittent uni-directionalmovement to said wheel.

Upon movement of staff 5 in a clockwise direction,

as viewed in Fig. l, cam 32 engages a tooth on wheel 34 and moves thelatter downwardly into the channel between the discs on member 31. Uponsubsequent counter-clockwise rotation of the staff, as explained above,cam 33 engages the same tooth and rotates wheel 34 further in the samedirection, and thereby moves the next tooth on the wheel into positionfor engagement by cam 32 and the cycle is repeated.

It will be seen that escapement wheel 34 is stationary at the moment ofeach impact between a cam 32 or 33 and a tooth on the wheel.Additionally, the cam is moving at its maximum velocity at the moment ofeach impact. The kinetic energy of each impact is thus relatively highand is accordingly the cause of an appreciable lll part of the noise ofoperation. A large portion of such noise is eliminated in the presentnovel construction wherein the mass of the escapement wheel ismaterially reduced Without adversely affecting the efficiency ofoperation or the operating life of the parts. lt has heretofore been theuniversal practice to construct the escapement wheel of brass or similarresonant metals having a relatively high specific gravity and good soundtransmission qualities. In the novel structure comprehended by thisinvention, wheel 34 is made of a plastic, such as nylon, Lucite,Bakelite, or the like, or lighter metals, such as aluminum and magnesiumalloys, all of which have a considerably lower specific gravity thanbrass and are relatively inert to sound transmission. Another advantagein using plastic Wheels is that the same may be molded, whereas themetal wheels must be cut.

The present invention also contemplates novel means for mounting arotatable shaft, such as the shaft on which wheel 34 is secured, tothereby substantially eliminate undesirable radial and axial movementsthereof to insure uniform dead-beat escapement action and to providelong life lubrication while automatically effecting the desired optimumbraking, thereby eliminating the necessity for a separate braking means.In the form r shown, the worm shaft 35 on which wheel 34 is mounted hasa cone-shaped tip (Fig. 4) at each end thereof for engagement with apair of supporting brackets 45 and 46. The former of these, as shown, isa rigid right-angle bracket and is rigidly secured by rivets or othersuitable means to the upper surface of plate 6, as viewed in Fig. 2.

Bracket 46 is made of a rather thin gauge spring metal, such as springphosphor bronze, and may be either rigidly or adjustably secured to thesurface of plate 6. As illustrated, bracket 46 is piveted on said plateat 47 and the base thereof is slotted to receive a set screw 43 adaptedto hold the same in a variety of adjusted positions around the verticalpivot 47.

The resilient upstanding portion of bracket 46 is provided with a boreor opening i9 therethrough (Fig. 4), the diameter of which is just largeenough to receive the tip end of shaft 35. Preferably, this holeterminates in a slight chamfer to serve as a bearing seat and providesuitable annular surface contact for the conical end of the shaft. Theupstanding portion of rigid bracket 45 may be similarly bored andchamfered in axial alignment with bore 49 for receiving and supportingthe other end of shaft 3S which is also preferably cone-shaped. Theunlled portions of the bores in the brackets serve as oil reservoirswherein a supply of oil which will last for a considerable period ofoperation may be held by capillary action.

With the shaft mounting above described, the elimination of undesirableend play and radial movement of the Shaft and the provision of automaticbraking against reverse movement of the shaft are attained by placingthe upstanding spring arm of bracket 46 under an initial tension towardshaft 3S. Adjustment of this tension or pressure may be effected byslightly bending said spring arm at its juncture with the base of thebracket, or by adjusting the entire bracket about pivot 47. Proferably,tne bracket is so constructed and positioned that the upstanding portionthereof will be substantially vertical when the installation is completewith the proper pressure being exerted thereby endwise upon shaft 35.Since the braking pressure is applied at a comparatively small radius,

it will be observed that quite a wide variation of the end pressure ispermissible without adversely affecting the braking torque. Essentiallyconstant braking effort is thus assured without the necessity forcritical or sensitive adjustments by the operator. Thus, when the partshave been properly adjusted in the factory during initial assembly, thepressure, and hence the braking torque, will remain sufficientlyconstant for an indefinite period of operation. The spring support forthe shaft also compensates automatically for wear at the journals whichin prior constructions resulted in a loosening of the escapement wheelshaft and hence erratic operation thereof.

In the structure illustrated, the uni-directional, interhke carried byfore known and now in commercial use.

Although only a single embodiment of the invention has been illustratedin the accompanying drawings by way of example, it is to be expresslyunderstood that the same is not limited thereto.

Gand 7. The

3. In apparatus of the class described, a shaft having said cone-shapedends, the latter and the same angularity relative to the axis of theshaft and the dimensions of the parts being such that the conicalentrance to each bore makes annular surface contact with a cone-shapedagainst the other support to thereby effect a on the shaft.

4. An escapement a cone-shaped end of shaft out of contact at rightangles to each other.

6. Apparatus as defined in claim 2 wherein said support is resilient andis biased to apply continuous, axially directed pressure against saidshaft.

References Cited in the le of this patent UNITED STATES PATENTS 613,178Unz Oct. 25, 1898 687,776 Pain Dec. 3, 1901 1,371,654 Walmsley Mar. 15,1921 1,508,824 Schramm Sept. 16, 1924 1,950,243 House Mar. 6, 19341,965,762 Battegay July 10, 1934 1,972,461 Reiner Sept. 4, 19341,991,839 Favre-Bulle Feb. 19, 1935 2,266,015 Fink Dec. 16, 19412,377,276 Sperry et al May 29, 1945 2,420,827 Kennedy May 20, 19472,531,966 Berge Nov. 28, 1950 FOREIGN PATENTS 403,267 Great Britain Dec.21, 1933 346,752 Italy Mar. 5, 1937

